Biosorption of Ni(ii) and Pb(ii) by Phanerochaete chrysosporium from a binary metal system – kinetics

Abstract

The biosorption kinetics of Ni(II) and Pb(II) by the resting cells of a lignolytic white-rot fungus, Phanerochaete chrysosporium, from a binary metal system were investigated. Kinetic studies revealed that biosorption takes place in two stages: a rapid surface adsorption, within the first 30 min, and a slow intracellular diffusion till the end of the 3 h contact time. In the first minutes of contact solution pH decreased sharply, parallel to the fast metal uptake, probably because of the protons released by the biosorbent. As sorption equilibrium was reached, solution pH also reached an equilibrium level. Metal biosorption capacities increased as the initial metal concentrations (Ci) increased, independent of initial pH (pHi) and generally the metal with higher Ci had a higher uptake capacity. The results also show that some portion of the metal ions sorbed by P. chrysosporium was readily released to solution with a decrease in pH. At equilibrium, the maximum total metal uptake of P. chrysosporium was 109.5 mg/g and was reached at pHi 5. Under these circumstances Ni(II) and Pb(II) uptake capacities were 55.9 mg Ni/g and 53.6 mg Pb/g, respectively.



WaterSA Vol.27(1) 2001: 15-20